Combined Effects of Water Deficit, Exogenous Ethylene Application and Root Symbioses on Trigonelline and ABA Accumulation in Fenugreek

Secondary metabolites (SMs) have high economic impact thanks to their exploitability inchemical, pharmaceutical and cosmetic industries. Trigonella foenum-graecum has an importance dueto the production of bioactive compounds with pharmaceutical values. Among them, the alkaloidtrigonelline is known for its role in the treatment of dierent human diseases. SM accumulation isinfluenced by environmental factors but is modulated by the application of exogenous compounds.Ethephon, a precursor of the phytohormone ethylene, was already used to influence SM accumulation.Our work is aimed at evaluating the accumulation of trigonelline and the phytohormone abscisicacid (ABA) when three factors were combined: i) two levels of water regimes (well-watered andwater deficit), ii) ethephon treatments and iii) inoculation with an arbuscular mycorrhizal (AM)-basedinoculum also leading to nodulation. The content of trigonelline and ABA was significantly aectedby symbioses, showing high accumulation in AM-colonized plants irrespective of the water regimesapplied. In terms of trigonelline accumulation with respect to ethephon treatments, while symbioticplants showed a dose-dependent trend, non-symbiotic plants showed a significantly dierence onlywhen 550 ppm of ethephon was applied. In conclusion, our work provides new information on theeects of both ethephon and symbioses on plant growth and accumulation of valuable compounds,such as trigonelline, in fenugreek.